Mast cell desensitization inhibits calcium flux and aberrantly remodels actin
W.X. Gladys Ang, … , A. Wesley Burks, Soman N. Abraham
W.X. Gladys Ang, … , A. Wesley Burks, Soman N. Abraham
Published September 26, 2016
Citation Information: J Clin Invest. 2016;126(11):4103-4118. https://doi.org/10.1172/JCI87492.
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Mast cell desensitization inhibits calcium flux and aberrantly remodels actin

Abstract

Rush desensitization (DS) is a widely used and effective clinical strategy for the rapid inhibition of IgE-mediated anaphylactic responses. However, the cellular targets and underlying mechanisms behind this process remain unclear. Recent studies have implicated mast cells (MCs) as the primary target cells for DS. Here, we developed a murine model of passive anaphylaxis with demonstrated MC involvement and an in vitro assay to evaluate the effect of DS on MCs. In contrast with previous reports, we determined that functional IgE remains on the cell surface of desensitized MCs following DS. Despite notable reductions in MC degranulation following DS, the high-affinity IgE receptor FcεRI was still capable of transducing signals in desensitized MCs. Additionally, we found that displacement of the actin cytoskeleton and its continued association with FcεRI impede the capacity of desensitized MCs to evoke the calcium response that is essential for MC degranulation. Together, these findings suggest that reduced degranulation responses in desensitized MCs arise from aberrant actin remodeling, providing insights that may lead to improvement of DS treatments for anaphylactic responses.

Authors

W.X. Gladys Ang, Alison M. Church, Mike Kulis, Hae Woong Choi, A. Wesley Burks, Soman N. Abraham

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Figure 6

Distinct actin reorganization in desensitized cells.

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Distinct actin reorganization in desensitized cells. (A) Serglycin (SG)–...
(A) Serglycin (SG)–mCherry (red) RBL-2H3 cells were plated on coverslips before desensitization and/or challenge with Ag for 5 minutes followed by fixation and staining for CD63 (blue) and F-actin (green). Images are representative of at least 3 independent experiments. Scale bars: 10 μm. (B) 2 × 106 BMMCs per sample were desensitized (DS) or untreated (Ag) before challenge with Ag for 0, 1, or 5 minutes. Lysates were immunoblotted for phosphorylated and total cofilin. Blots represent at least 4 experiments. Densitometry data were expressed as percentage phosphorylated protein compared with total, then normalized to control (IgE). Data were analyzed via 1-way ANOVA. Data represent SEM. *P < 0.05.